Mobility management in a system such as LTE (E-UTRAN) comprises IDLE mode management and ACTIVE mode management of users. In Idle mode the mobile is moving around in the mobile network without sending or receiving data, its position is known by the network to an approximate degree, e.g. it may be known in which tracking/routing area the mobile is located, but not it's exact cell.
In active mode the UE is moving around and at the same time sending and receiving data (continuously or intermittently). The location of the UE needs to be known by the network (NW) down to the very cell and base station. For a system, in particular a system with small cells such as LTE (Long Term Evolution), for user equipments (UE) in active mode there may be a problem in that there will be very much signaling in the NW in order to update the NW with the current location of the UE. In a hierarchical NW system, e.g. GPRS or Mobitex, there will be signaling up the NW distribution tree to update routing information only in the down-most node common to the new and the old cell. Therefore the NW signaling will be limited. SAE/LTE on the other hand, is specified as a flat IP architecture system and the first common node is at the same time the top node. Tunnel switching and related signaling will be very frequent in the top Core NW nodes.
Therefore, there is a need to specify a solution that makes more efficient mobility signaling for UEs in active mode for flat architecture systems such as SAE/LTE.